It is known that nitrous oxide (“NOx”) emission output is directly related to combustion flame temperature within a gas turbine combustor. To control that temperature and in turn the NOx output, water can be added to the combustion process. High volumes of water are typically used for controlling NOx emissions with some of the water being recirculated rather than injected into the combustor. Known systems for controlling water flow use a centrifugal pump with valving to throttle the forward flow to meet a set rate of gallons per minute. Recirculation is typically required because the pump generates a higher flow rate of water than is needed for injection into the combustor. The recirculated water may be pumped through a water return line to a holding tank remote from the turbine.